1. Field of the Invention
The present invention relates to a process for the manufacture of N (polyoxyalkyl)-N-(alkyl)-amines by reacting in one step a polyetheramine in which the amine groups are predominently primary in character with a low molecular weight, sterically hindered alcohol. These N-(polyoxyalkyl)-N-(alkyl)-amines are characterized by a high content of secondary amine groups.
2. Prior Art
Amination of polymeric alcohols with ammonia under various reaction conditions to produce primary amines is well known. Similarly, it is also well known that low molecular weight primary amines react with low molecular weight alcohols to form secondary amines, and low molecular weight secondary amines react with low molecular weight alcohols to form tertiary amines.
In U.S. Pat. No. 4,638,336 amines are prepared from an aliphatic alcohol and, as aminating agents ammonia, a primary amine and a secondary amine. When the secondary amine was used, the product was a tertiary amine.
In DE 3,539,266 tertiary amines were prepared from the reaction of secondary amines with alcohols in the presence of a hydrogenation/dehydrogenation catalyst.
In JP 62 51646 alpha, omega ditertiary amines formed from the reaction of an alpha, omega diol and a secondary amine in the presence of hydrogen and copper or cobalt catalyst.
In DE No. 3,432,015 very high tertiary amines were derived from the reaction of dimethylamine amine and a C12 alcohol. Copper/tin and other catalysts were discussed.
In U.S. Pat. No. 4,625,063 high purity tertiary amines formed from the reaction of an alcohol and a primary or secondary amine where the catalyst contained copper/nickel and a Group VIII metal.
In JP 59-222,448 alkyldimethylamines were produced from the reaction of dimethylamine and an alcohol.
In U.S. Pats. Nos. 4,404,404 and 4,409,399 tertiary amines were derived from the reaction of dimethylamine and dodecanol in the presence of copper on nickel oxide catalysts.
In U.S. Pat. No. 4,442,306 tertiary amines were produced from the reaction of alcohol and a secondary amine using a copper formate catalyst.
In JP No. 62 33138 there is described a special catalyst for controlling the reaction of secondary amines with alkane diols to give mono- and ditertiary amine products.
However, no art teaches the direct manufacture of polyetheramines having a high secondary amine content by directly reacting a polyol with a primary amine. In fact, the only related art, U.S. Pat. No. 4,686,242, teaches that only low levels (less than 40% of total amine) of secondary amine terminated polyethers can be obtained when one attempts to directly manufacture the secondary polyetheramine from primary amines and a polyether polyols.
Another method for preparing a secondary polyetheramine is described in U.S. Pat. No. 4,286,074, where a pre made primary polyetheramine is first allowed to react with acetone to form the resulting ketimine. This product is hydrogenated to the expected high secondary amine containing product. Although this process is technically feasible for polyetheramines of other molecular weights and functionalities, it is not very efficient or economically attractive and the current commercial suppliers of primary polyetheramines are quite limited.
These patents clearly indicate that it is generally expected from the art that a primary amine, when reacted with an alcohol, should form the art expected secondary amine. However, as noted in U.S. Pat. No. 4,686,242, the reaction actually generates a product which is predominantly primary amine in character. It has now been discovered that it is possible to overcome this limitation by reacting a polyetheramine in which the amine groups are predominantly primary in character with a sterically hindered, low molecular weight alcohol to obtain high levels of secondary amine termination on the polyetheramine.